LOCATION OVERLOOK AZEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Pachic Argiustolls
TYPICAL PEDON: Overlook very gravelly coarse sandy loam - rangeland and recreation. (Colors are for dry soil unless otherwise noted.)
A1--0 to 2 inches; grayish brown (10YR 5/2) very gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy structure parting to weak very fine granular; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; few very fine irregular and tubular pores; 40 percent gravel; noneffervescent; slightly acid (pH 6.2); abrupt smooth boundary.
A2--2 to 6 inches; brown (10YR 4/3) very gravelly sandy clay loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; common very fine and few fine roots; few very fine irregular and tubular pores; 35 percent gravel; noneffervescent, neutral (pH 6.8); clear smooth boundary. (Combined thickness of the A horizons is 2 to 10 inches)
Bt1--6 to 18 inches; dark grayish brown (10YR 4/2) very gravelly sandy clay loam, very dark brown (10YR 2/2) moist; moderate coarse subangular blocky structure parting to moderate fine subangular blocky; slightly hard and hard, very friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine and few fine irregular and few very fine and fine tubular pores; common faint and few distinct clay films on faces of peds and in pores; 35 percent gravel; noneffervescent; slightly alkaline (pH 7.4); clear wavy boundary.
Bt2--18 to 30 inches; dark grayish brown (10YR 4/2) very gravelly sandy clay loam, very dark brown (10YR 2/2) moist; moderate coarse subangular blocky structure parting to moderate fine subangular blocky; slightly hard and hard, very friable, moderately sticky and moderately plastic; common very fine roots; common very fine, few fine, medium and coarse irregular and common very fine and few fine tubular pores; common faint and distinct clay films on faces of peds and in pores; 35 percent gravel; few insect tunnels and casts; noneffervescent; slightly alkaline (pH 7.4); abrupt irregular boundary.
2Bt3--30 to 60 inches; yellowish brown (10YR 5/4) very gravelly sandy clay loam, dark yellowish brown (10YR 3/4) moist; weak very coarse subangular blocky structure parting to moderate medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; few fine irregular pores; common faint clay films on faces of peds and few faint clay films in pores; 40 percent gravel, 10 percent cobble, 3 percent stones; tonguing of Bt2 horizon into the upper part of this horizon; noneffervescent; slightly alkaline (pH 7.4). (Combined thickness of the Bt horizons is 37 to 55 inches)
TYPE LOCATION: Fort Bowie National Historic Site; located at a latitude of 32 degrees, 9 minutes, 3 seconds North and longitude of 109 degrees, 27 minutes, 2 seconds West.
RANGE IN CHARACTERISTICS:
Soil moisture: Intermittently moist in some part of the soil moisture control section during July - September and December - February. Driest during May and June. Aridic ustic soil moisture regime.
Soil Temperature: 59 to 64 degrees F.
Rock fragments: more than 35 percent
Clay content: 18 to 35 percent
Organic matter: 1 to 5 percent
Lower boundary of mollic epipedon: 20 to 34 inches
Lower boundary of argillic horizon: 27 to 35 inches
Some pedons have a C horizon below the Bt horizon
A horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Bt horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 2 through 4 moist
Chroma: 2 through 4, dry or moist
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Overlook soils are on fan terrace summits, shoulders, and side slopes at elevations of 4700 to 5000 feet. Slopes range from 8 to 30 percent. These soils formed in alluvium derived from granite. The mean annual precipitation is 16 to 20 inches and occurs as thunderstorms during July to September and as gentle rains during December to February. The mean annual air temperature is 57 to 62 degrees F. The frost free period is 180 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Budlamp and Siphoncan soils. Budlamp and Siphoncan soils are less than 20 inches deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Used for livestock grazing, wildlife habitat and recreation. Vegetation includes mesquite, one seed juniper, turpentine bush, cholla, prickly pear, agave, snakeweed, hairy grama and black grama.
DISTRIBUTION AND EXTENT: Southern Arizona. Overlook soils are of limited extent. MLRA is 41. The name is from nearby Overlook Ridge.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cochise County, Arizona; Soil survey of Fort Bowie National Historic Site; 1996.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 30 inches (A1, A2, Bt1, Bt2 horizons)
Argillic horizon - The zone from 6 to 30 inches (Bt1, Bt2 horizons)